The present invention relates generally to the field of electrosurgery, and more particularly to methods and apparatus for the controlled removal of a target tissue during an electrosurgical procedure. The present invention further relates to an apparatus including a rotating member housed within a shaft, and an active electrode adapted to electrosurgically remove tissue, via molecular dissociation of tissue components, during rotation of the rotating member.
Surgical instruments that mechanically remove tissue by contact with a rotating burr, blade, etc., are well known in the art, and have been used for both open and closed surgical procedures. Such instruments, however, suffer from a number of disadvantages. Firstly, the cutting edge (e.g., blade) tends to dull fairly rapidly during use, such that it may be necessary to change the cutting component of the instrument during the course of a single procedure. As a result, the time and cost of performing the procedure is increased. A further disadvantage associated with rotary cutting, drilling, and shaving devices is that they typically result in substantial bleeding as the tissue is removed. Such bleeding must be controlled in order to prevent obstruction of the surgeon's view of the surgical site. Attempts have been made to control bleeding by the application of a tourniquet, by administering the vasoconstrictor epinephrine, and, in the case of certain arthroscopic procedures, by pressurizing the joint cavity. Each of these approaches to control bleeding is associated with one or more disadvantages. Establishment of hemostasis following mechanical removal of tissue has also been achieved by the application of a separate electrocautery device to bleeding blood vessels. However, the use of an ancillary electrocautery device typically involves removal of the mechanical cutting device, thereby necessitating a delay in coagulating the bleeding vessels, and consequently requires additional time, and associated costs, for completing the procedure as a whole.
A number of surgical devices are known that include a movable shaving or cutting mechanism and which also incorporate an electrode for cauterizing or cutting tissue. For example, U.S. Pat. No. 5,941,876, to Nardella et al., discloses an inner, rotating tissue-affecting element comprising an electrically conductive shaft, and a non-conductive material disposed over predetermined regions of an outer surface of the shaft, wherein a distal portion of the outer surface of the shaft is exposed to define an active electrode surface. Removal of tissue is by the mechanical action of the rotating shaft and by electrosurgical energy delivered to the tissue by an energized cutting edge. U.S. Pat. No. 6,036,681 (to Hooven) discloses a method and apparatus for morcelating tissue. The apparatus includes an outer tube and an inner tube that may be caused to rotate by a motor. Various electrode configurations are disclosed for cutting, slicing, or otherwise sub-dividing excised tissue via RF electrical energy.
Other devices having both a movable cutting device and an electrode are disclosed, e.g., in U.S. Pat. No. 5,810,809 to Rydell; U.S. Pat. No. 6,193,715 to Wrublewski et al.; and U.S. Pat. No. 6,032,673 to Savage et al. See also, U.S. Pat. No. 4,815,462 to Clark. All patents, patent applications, and publications mentioned in this application are incorporated by reference in their entirety.
There is a need for an instrument that removes target tissue electrosurgically in a highly controlled manner, and which can also provide hemostasis at the surgical site. There is a further need for an inexpensive, yet reliable and effective rotary tissue removal device that removes tissue by the molecular dissociation of tissue components during the application of electrical energy to an electrode of the instrument.